The objective of this research is an assessment of the damage produced by light generated increases of temperature in the eye. Temperature and local electroretinograms will be measured "in vivo" in rabbits and monkeys, with microprobes (10 to 20 microns in diameter) for irradiation durations from 20 nsec. to 10 minutes and for irradiation intensities from below burn threshold to suprathreshold levels. Exposures will be obtained from a ruby laser and a shuttered Argon C. W. laser. The microprobes will permit measurement of the actual irradiance profile at the retina. This experimental data will be used to verify and/or improve the suitability of existing models for the computation of retinal temperature and the rate process of light induced damage. Knowledge of ocular damage (a visible lesion or a decrement in the function of the photoreceptors as measured by the local ERG) as a function of retinal temperature would permit the extensive use of the temperature and rate process models for the prediction of ocular damage due to any coherent or incoherent source in the visible spectrum.